1. Field of the Invention
The present invention relates to a mobile communication system. More particularly, the present invention relates to a method and apparatus of a mobile terminal for reporting a maximum transmission power to assist scheduling decision making of a base station in the wireless communication system.
2. Description of the Related Art
Mobile communication systems were developed to provide subscribers with voice communication services on the move. With the advance of technologies, the mobile communications have been evolved to support high speed data communication services as well as the standard voice communication services.
Recently, as a next generation mobile communication system, Long Term Evolution (LTE) is being standardized by the 3rd Generation Partnership Project (3GPP). LTE is designed to provide for a downlink speed of up to 100 Mbps. In order to fulfill the requirements of the LTE systems, studies have been done of various aspects including minimization of the number of involved nodes in the connections and placing the radio protocol as close as possible to the radio channels.
In the meantime, unlike the standard voice service, most data services are allocated resources according to the amount of data to be transmitted and channel conditions. Accordingly, in the wireless communication system such as a cellular communication system, it is important to manage resource allocation based on the resource scheduled for data transmission, channel condition, and a data amount to be transmitted. This is true even in the LTE system, and the base station scheduler manages and assigns radio resources.
In the LTE system, the User Equipment (UE) provides the evolved Node B (eNB) with scheduling information to assist uplink scheduling. The scheduling information includes a Buffer Status Report (BSR) and a Power Headroom Report (PHR). Particularly, PHR is used to prevent the total transmit power from exceeding the maximum transmit power limit when the eNB assigns the resources of uplink transmission of the UE. Since inaccurate PHR information causes scheduling errors or interference to other transmissions, it is very important for the eNB to interpret the PHR reported by the UE correctly.